Electric motor-driven adjustment drive

ABSTRACT

The invention relates to an electromotive adjustment drive which is operated by a safety voltage, for instance, an adjustment drive for the adjustable components of pieces of furniture. The adjustment drive is equipped with a hand-operated device and a control unit which is operated with the device and connected by at least one cable to a voltage source to which the mains voltage can be supplied. The adjustment drive is so configured as to allow an electrical separation between the voltage source and the transformer, when the adjustment drive is not in operation, without requiring special cables. Furthermore, the adjustment drive should be configured in such a way that the item equipped with the adjustment drive does not contain any cables or lines to which mains voltage is supplied. According to the invention, there is provided a power supply module ( 12 ) which is spatially separated from the control unit ( 14 ) and arranged between the control unit ( 14 ) of the adjustment drive ( 11 ) and the voltage source. Mains voltage is supplied to the power supply module on the input side and safety voltage flows out on the output side. The power supply module ( 12 ) contains at least one transformer ( 18 ) and an upstream power disconnection circuit ( 19 ). The power chord ( 16 ) leading from the voltage source to the power supply module ( 12 ) is detachably connected by means of a plug-and-socket connector. The power chord is fitted with a plug and the housing of the power supply module ( 12 ) is equipped with a socket receptacle or a jack. The transformer ( 18 ) is an electronic transformer.

[0001] The invention relates to an electromotive adjustment drive whichcan be operated by a safety voltage, in particular a drive for a pieceof furniture, and which is equipped with a control unit operated by ahand-operated device and connected by at least one cable with a voltagesource supplied with the mains voltage. Adjustment drives of the typeinvolved here are operated by low-voltage motors having a supply voltageprovided by a transformer connected to the electric power grid. Themotors may be operated by alternating voltage as well as direct voltage.Safety reasons dictate however that the voltage is decreasedsubstantially. Adjustment drives of standard construction havetransformers integrated in the housing of the adjustment drive. As aconsequence, the current-carrying cable between the voltage source andthe transformer is live. When the adjustment drive is utilized tooperate a piece of furniture, many users perceive the presence of liveelectric or electronic components or component groups in the piece offurniture, e.g. a chair or a bed, as objectionable.

[0002] It has therefore been proposed to arrange the transformer outsidethe housing of the adjustment drive, even in those cases when theavailable installation space is too small to accommodate the adjustmentdrive, because the removal of the transformer renders the dimensions ofthe adjustment drive smaller. Such detached transformers are also calledas add-on transformers. Up to a particular output, the transformer mayalso be configured as power plug so as to be positioned in immediateproximity to a socket receptacle. Furthermore, this configuration hasthe drawback that the mains voltage is continuously supplied to thetransformer. No-load losses are converted into heat, thereby incurringadded costs. It has therefore been proposed to separate the transformerfrom the voltage source through disconnection from the voltage sourceduring the conceivably very long idle period. This, however, entails thedrawback that the power disconnection requires for control a particularcable which must be so configured that the mains voltage as well as thecontrol voltage can be applied. Another option would be to lay twodifferent cables; this requires however a complicated insulation so thatcosts are further increased.

[0003] The control unit is typically integrated either in the housing ofthe adjustment drive or in a housing which is connected to the housingof the adjustment drive. The hand-operated device is normallyimplemented as a hand switch having several push buttons and outputtingsignals which are transmitted to the control unit via a cable or alsowireless.

[0004] The invention is based on the object to so configure anelectromotive adjustment drive of the afore-described type that theseparation between the voltage source and the transformer is possible atshutdown of the adjustment drive, without requiring a special cable.Moreover, the adjustment drive is so configured that the item equippedwith the adjustment drive does not have any cable or lines which aresupplied with the mains voltage.

[0005] The posed object is attained by providing between the controlunit and the voltage source a power supply module which is spatiallyseparate from the control unit and has an input side for input of themains voltage and an output side for output of a safety voltage, and byproviding the power supply module with at least one transformer and anupstream power disconnection circuit.

[0006] The solution according to the invention thus realizes that themains voltage is supplied only to the cable between the voltage sourceand the power supply module. The cable connecting the power supplymodule with the control unit can thus be implemented as an inexpensivelow-voltage cable. The cable between the voltage source and the powersupply module can be made extremely short. Moreover, any commerciallyavailable cable can then be used. This configuration eliminates theotherwise required special cable. Furthermore, the adjustment drive,installed in an item, for example a piece of furniture, is supplied nowonly with the safety voltage so as to realize a greatest possiblesafety. Through provision of the power disconnection circuit, thetransformer and optionally further electric or electronic components aswell as the cable connection and the adjustment drive itself includingthe control unit are currentless when not in operation. The adjustmentdrives concerned here are shipped to many countries. It is known thatnot only voltages and frequencies vary but also the electric connectors.It is therefore provided to employ plug-and-socket connectors fordetachably connecting the power supply module and the power chord, whichleads to the voltage source, and to configure preferably the power chordwith a plug and the housing of the power supply module with a socketreceptacle or jack. It is then easily possible to exchange the powerchord with the various national plugs. Thus, storage for the powersupply modules is reduced so that costs, too, are reduced.

[0007] It is especially advantageous to use an electronic transformer astransformer because it affords the possibility to use for various anddiverse national input voltages a respective power pack having a fairlylarge input voltage range. This further reduces storage. Suitably, theindividual functional units are made of modular construction so that itbecomes possible to retrofit through addition of single modules. Thesemodules can then be assembled in a most simple manner through attachedconnectors to a structural unit, without the need for mechanicalconnecting elements. The modular configuration has the further advantagethat the power supply module can be modified later or even expanded.Advantageously, the power disconnection circuit includes at least one,preferably two, switching elements. In this way, it is possible in amost simple manner to implement the separation from the mains voltage.Especially advantageous is the provision of a cable to connect the powerdisconnection circuit for operation with the hand-operated device. Asthe hand-operated device is situated in the grip area of a person,actuation can be carried out extremely simple and ergonomicallybeneficial. The electromotive adjustment drives involved here may beequipped with d.c. motors as well as a.c. motors. When using d.c.motors, there is provided a rectifier and a filter element downstream ofthe transformer. Rectification of the alternating current is then alsorealized in the power supply module. Suitably, an emergency voltagesource is connected downstream of the transformer. This may be, forexample, a battery or an accumulator. As such voltage sources must bereplaced occasionally, replacement becomes extremely simple because thepower supply module is easy to access. In the event, several cables arerequired between the power supply module and the control unit, the powersupply module is provided on its output side with a cable unitingelement which may be provided also, for example, with a socketreceptacle so that a single cable with a respective number of wires forconnection to the control unit can be used. The individual components ofthe modular unit are dependent on the function to be met by theadjustment drive and possibly on safety regulations that have to beobserved.

[0008] The invention will now be described in more detail with referenceto the attached drawings, in which:

[0009]FIG. 1 is an exemplified embodiment of an electromotive adjustmentdrive equipped with a power supply module;

[0010]FIG. 2 is a possible embodiment of the power supply module; and

[0011]FIG. 3 is a power supply module of modular construction;

[0012]FIG. 4 is a power supply module according to FIG. 3, however witha voltage supply for the power disconnection circuit.

[0013] In the illustrated exemplified embodiment, the electromotiveadjustment drive 10 includes a linear drive 11 having a housing whichaccommodates all functional parts including a drive motor. Theelectromotive adjustment drive 10 is further equipped with a powersupply module 12 and a hand-operated device 13 in the form of a handswitch. Attached to the housing of the linear drive 11 is further acontrol unit 14. As clearly shown in FIG. 1, the power supply module 12is positioned at a distance to the linear drive 11 such that it isdisposed also outside of an item in which the linear drive 11 isinstalled. The connection between the control unit 14 and the powersupply module 12 is implemented by a, preferably, multicore cable 15.The power supply module 12 should be disposed as close as possible to avoltage source. The connection between the voltage source and the powersupply module 12 is realized by a power chord 16 which is equipped witha plug 17.

[0014] In the configuration according to FIG. 2, the power supply moduleincludes three components, namely a transformer 18, which, preferably,is an electronic transformer, a power disconnection circuit 19 placedupstream of the transformer 18, and a rectifier circuit 20 which furtherincludes a filter element. In the exemplified embodiment, the powerdisconnection circuit 19 is activated via a control cable 21 which isconnected, preferably, to the hand-operated device 13. The powerdisconnection circuit 19 includes two switches 19 a and 19 b in parallelconnection. FIG. 2 shows the switches 19 a, 19 b open, this correspondsto the idle state of the linear drive 11. The circuit diagram shows thatall components, which are disposed downstream of the power disconnectioncircuit 19 and can be supplied with current, are currentless. Thetransformer 18, the power disconnection circuit 19 and the rectifier 20may be arranged in a common housing.

[0015]FIG. 3 shows a modular construction of the power supply module 12.Same parts are designated by same reference characters. In contrast tothe configuration according to FIG. 3, this configuration is furtherequipped with an emergency power supply 20 a, for example a battery oran accumulator, as well as with a cable uniting element 22. Theindividual components 18 to 22 may be so designed that they can belocked or clipped together without mechanical connecting elements. Themodular construction is indicated by the vertical, dash-dotted lines.FIG. 3 shows further that the power chord 16 can be connected by aplug-and-socket connector 23, for example by a plug and a socketreceptacle, with the power disconnection circuit 19. The same is truealso for the cable 15 which is connected via plug-and-socket connectors24 with the cable uniting element 22.

[0016] The power supply module 12 should at least contain the powerdisconnection circuit 19 and the transformer 18. The configuration andthe number of the remaining components depend on the function to be metby the drive 11. For example, a rotary drive may be used as well as adual drive which is equipped with two drive motors. The voltage supply19 c for the power disconnection circuit 19 is realized by an auxiliaryvoltage source either from the electrical power grid through connectionof the contacts 19 a, 19 b of the power disconnection circuit 19,whereby a secondary transformer 18 a transforms the voltage. As analternative, it is also possible to use as auxiliary voltage source abattery or an accumulator which is located in the control unit 14. Thisis implemented via a connection 19 d of the auxiliary voltage source 20a. Especially advantageous. The modular construction and the spatialseparation of the apparatus have an especially advantageous effect sothat a change of the auxiliary voltage source can be carried in anextremely simple manner unlike conventional constructions.

[0017] The invention is not limited to the illustrated exemplifiedembodiment. Essential is the provision of a power supply module 12 whichis spatially separated from the control unit 14 and disposed between thecontrol unit 14 of the drive 11 and the voltage source and which has aninput side for input of the mains voltage and an output side for outputof the safety voltage.

1. Electromotive adjustment drive which can be operated by a safetyvoltage, in particular a drive for a piece of furniture, and which isequipped with a control unit operated by a hand-operated device andconnected by at least one cable with a voltage source supplied with themains voltage, characterized in that there is arranged between thecontrol unit (14) of the drive (11) and the voltage source a powersupply module (12) which is spatially separate from the control unit(14) and has an input side for input of the mains voltage and an outputside for output of a safety voltage, and that the power supply module(12) has at least one transformer (18) and an upstream powerdisconnection circuit (19).
 2. Electromotive adjustment drive accordingto claim 1, characterized in that the power supply module (12) and thepower chord (16) leading to the voltage source are detachably connectedto one another by plug-and-socket connectors, and that it is preferredto provide the power chord with a plug, and to provide the housing ofthe power supply module (12) with a socket receptacle or a jack. 3.Electromotive adjustment drive according to claim 1 or 2, characterizedin that the transformer (18) is an electronic transformer. 4.Electromotive adjustment drive according to one or more of the precedingclaims 1 to 3, characterized in that the power disconnection circuit(19) includes at least one, preferably two, switching elements (19 a, 19b).
 5. Electromotive adjustment drive according to one or more of thepreceding claims 1 to 4, characterized in that the power disconnectioncircuit (19) is connected for operation by a cable (21) with thehand-operated device(13).
 6. Electromotive adjustment drive according toone or more of the preceding claims 1 to 5, characterized in that arectifier (20) and, preferably, a filter element are connecteddownstream of the transformer (18).
 7. Electromotive adjustment driveaccording to one or more of the preceding claims 1 to 6, characterizedin that there is connected downstream of the transformer (18) anemergency voltage source (20 a) which is preferably formed by a batteryor an accumulator.
 8. Electromotive adjustment drive according to one ormore of the preceding claims 1 to 7 characterized in that the powersupply module (12) has an output side provided with a cable unitingelement (21).
 9. Electromotive adjustment drive according to claim 8,characterized in that the power supply module (12) is connected byplug-and-socket connectors to the cable (15) which leads to the controlunit (14).
 10. Electromotive adjustment drive according to one or moreof the preceding claims 1 to 9, characterized in that the components(18-22) forming the power supply unit (12) have a modular structure andare connected with one another preferably without mechanical connectingelements.
 11. Electromotive adjustment drive according to one or more ofthe preceding claims 1 to 10, characterized in that the voltage supply(19 c) of the power disconnection circuit (19) is realized by anauxiliary voltage source, for example a secondary transformer (18 a)which is powered from the electrical power grid or implemented by abattery or accumulator provided in the control unit (14). 12.Electromotive adjustment drive according to claim 11, characterized inthat the voltage supply (19 c) of the power disconnection circuit (19)is electrically connected via a connection (19 d) with the emergencyvoltage source (20).